Inorganic filler material, particularly vitreous beads, are widely used as additives in polymeric compositions, such as those deposited on highways to provide reflective markers, for instance, edge and lane striping, signs, etc. As is well known, it has become common practice to drop small glass spheres onto a painted line on a highway while the paint is still tacky such that the spheres are partially embedded in the paint when it has dried. The spheres render the line or other marker retroreflective and reflect the light from headlights so that the marker is more visible to the motorist. In some cases the spheres are embedded in spherical or irregularly shaped plastic granules prior to being contacted with the paint in the manner disclosed in U. S. Pat. Nos. 3,252,376 and 3,254,563, for example, in an effort further to improve the reflectivity of the marker.
It is also known to provide inorganic filler material having a catalyst fixed to the surface of the filler material to effect polymerization of a polymerizable material upon contact of the catalyst-containing filler material with the polymerizable material in the manner disclosed in British published patent application 88 10 801.4. The catalyst is fixed to the surface of the filler material by means of a fixing agent adhered to the filler material. A particularly preferred catalyst is benzoyl peroxide. However, it appears that particulate material containing benzoyl peroxide and the fixing agents disclosed in such patent application could have been rendered unstable by the use of organic liquids. These solvents and/or binding agents could have destabilized the benzoyl peroxide dispersion as they bound the benzoyl peroxide to the filler surface. The incorporation of conventional stabilizing agents for benzoyl peroxide, such as taught in U.S. Pat. No. 4,917,816, in order to give some stability to the particulate material yields particles which, in volume quantities, do not have good flowability.
It would be a substantial advance to provide inorganic filler material incorporating benzoyl peroxide catalyst, which is both stable and free-flowing for convenient processing, and effects catalysis of the curing of a polymerizable material in which the filler material is included.